1. Field of the Invention
The present invention relates generally to remote control and navigation of vehicles, especially vehicles in a convoy.
2. Description of the Background Art
Convoys, such as re-supply convoys, generally require at least one driver per truck. The trucks generally follow a lead truck over a course. The driver of the lead truck determines the course, and the drivers of each succeeding truck follow behind the lead truck. Since only the lead truck is operating independently, putting a driver in each of the succeeding trucks is a waste of manpower.
Different strategies for guiding unmanned vehicles have been tried. One strategy is the electronic towbar. An electronic towbar is similar to the adaptive cruise control of automotive use, wherein a vehicle senses the vehicle in front of it and follows at a predetermined distance. The sensing may be via reflection of an RF signal. Over rough terrain, however, or during severe maneuvers or weather conditions, the following vehicles may lose track of the vehicle in front of them. Electronic tow bars are also difficult to use in sharp turns, wherein steering and braking are performed simultaneously. Furthermore, simple following of a leading vehicle fails to keep the trailing vehicle on the road, since navigation of the trailing vehicle directly toward the lead vehicle will result in corners being cut.
Another strategy used for guiding unmanned vehicles is to mark a course for the vehicles to detect and follow. The markers for such a course may be nails in the ground or a wire. This works well for a fixed course that will be repeatedly traversed by vehicles. It is not a solution, however for a variable course over an unknown piece of terrain.
U.S. Pat. No. 5,532,690 to Hertel, for example, the disclosure of which is incorporated by reference, describes monitoring and bounding the path of a ground vehicle using a global positioning signal (GPS). If the vehicle ventures outside its area of permitted operation, a kill switch is activated to disable the vehicle. Hertel, however, describes no means of guiding an unmanned vehicle.
U.S. Pat. Nos. 5,646,843, 5,646,845, and 5,838,562 to Gudat et al., the disclosures of which are incorporated by reference, describe vehicle navigation either along a stored path, autonomously between two preset points, or along a path transmitted from a central location, using GPS. Gudet, however, describes no vehicle driven over an arbitrary course that transmits waypoints to a follower vehicle, so the follower vehicle can follow the same course.
U.S. Pat. No. 5,711,3838 to Davies et al., the disclosure of which is incorporated by reference, describes a robotic golf cart. The golf cart follows navigation rules according to a stored map. Davis, however, does not describe transmitting waypoints from one golf cart to a following golf cart, so that the following golf cart tracks the same course.
U.S. Pat. No. 5,872,526 to Tognazzini, the disclosure of which is incorporated by reference, describes a GPS collision avoidance system in which a vehicle operator of one vehicle receives GPS data transmitted by other vehicles. The positions of the other vehicles are then displayed on a monitor. Tognazzini, however, does not describe transmitting waypoints from a leader vehicle to a following vehicle, so that the following vehicle tracks the same course.
U.S. Pat. No. 5,917,405 to Joao, the disclosure of which is incorporated by reference, describes a theft deterrent system for a vehicle. The vehicle""s location may be determined from a control apparatus by GPS, and certain functions may be performed, such as disabling the ignition. Joao, however, does not describe guiding the vehicle to a waypoint broadcast by another vehicle.
U.S. Pat. No. 5,921,708 to Grundl et al., the disclosure of which is incorporated by reference, describes a pavement vehicle convoy in which a follower vehicle is remotely controlled by a leader vehicle. Grundl, however, does not describe guiding the follower vehicle to a waypoint broadcast by the leader vehicle.
U.S. Pat. No. 5,921,708 to Suman et al., the disclosure of which is incorporated by reference, describes a RF vehicle remote control that performs such functions as vehicle tracking via GPS and locking doors. Suman, however, does not describe guiding the vehicle to a waypoint broadcast by another vehicle.
There remains a need in the art, therefore, for a remote control vehicle navigation system that allows a leader vehicle to choose an arbitrary course and be followed along that course by follower vehicles.
The invention provides a system for the remote control of self-propelled vehicles in which a leader vehicle is selected from among a group of similarly equipped vehicles and driven along an arbitrary course by a human driver, taking a succession of GPS coordinate position fixes, or waypoints, along the way, and broadcasting the succession of way points to at least one unmanned follower vehicle from the other vehicles in the group.
The follower vehicle, which can take its own GPS coordinate position fixes, has a comparator for comparing the set of GPS coordinate fixes received from the leader vehicle with its own position, and uses servo-actuators to operate its steering, drive, and braking mechanisms to minimize the distance between its own GPS position and the position of each of the succession of waypoints in turn. The follower vehicle thus traverses the same course as the leader vehicle. All the vehicles in the group are equipped to fill either a leader role or a follower role. If the comparator, for example, is embodied in a computer, then the role of leader or follower can be assigned by programming some software.
An object sensor may be mounted on the follower vehicle to avoid collisions with the vehicle in front, or other objects, if, for example, the signal carrying the GPS coordinates transmitted from the lead vehicle is unavailable. The follower vehicle can also be made to re-transmit the set of GPS coordinates to further following vehicles, in the manner of a repeater.